1. Field of the Invention
The present invention is generally directed to the field of biometric imaging. In particular, the present invention is directed to a method for calibrating and correcting settings in a fingerprint scanner.
2. Related Art
Biometrics is a science involving the analysis of biological characteristics. Biometric imaging captures a measurable characteristic of a human being for identity purposes. See, e.g., Gary Roethenbaugh, Biometrics Explained, International Computer Security Association, Inc., pp. 1–34, (1998), which is incorporated herein by reference in its entirety.
One type of biometric imaging system is an Automatic Fingerprint Identification System (AFIS). Automatic Fingerprint Identification Systems are used for law enforcement purposes. Law enforcement personnel collect fingerprint images from criminal suspects when they are arrested. Law enforcement personnel also collect fingerprint images from crime scenes. These are known as latent prints.
Tenprint scanners are a common type of AFIS system. Tenprint scanners produce forensic-quality tenprint records of rolled and plain impression fingerprint images. Tenprint scanners must be sufficiently reliable to meet rigid image standards, such as NIST image requirements. Normal usage of the tenprint scanner over time, as well as variations in temperature, dirt and dust, etc., cause the performance level of the tenprint scanner to drift with respect to certain optimal settings. Settings needing periodic adjustment and correction include brightness, contrast, focus, and geometric distortion. What is needed is a system and method that periodically calibrates the tenprint scanner to maintain optimal settings. What is also needed is a system and method of calibration and correction that provides increased tolerances in the optical design of the tenprint scanner.